Triple heat management heat dissipation moisture-proof wood-plastic composite board and preparation method thereof

Abstract

This application relates to a triple thermal management heat dissipation and moisture-proof wood-plastic composite board and its preparation method, belonging to the technical field of wood-plastic composite materials. The triple thermal management heat dissipation and moisture-proof wood-plastic composite board consists of a radiation / reflection surface layer, a thermally conductive wood-plastic core layer, and a thermally conductive and waterproof bottom layer. It achieves summer cooling by combining three thermal management strategies: strong solar reflection, high thermal radiation, and excellent thermal conductivity, thereby improving thermal comfort upon direct contact with the human body. The bottom layer further provides waterproofing and moisture-proofing. The wood-plastic composite board provided by this application can achieve heat dissipation and cooling in summer while also providing moisture protection. It has a reasonable structural design and a simple manufacturing process, making it suitable for various outdoor decorative wood-plastic boards, railings, garden benches, exterior wall construction, and other applications.

Description

Technical Field

[0001] This application relates to a triple thermal management heat dissipation and moisture-proof wood-plastic composite board and its preparation method, belonging to the field of wood-plastic composite material technology. Background Technology

[0002] With increasing global environmental awareness, people are paying more and more attention to the research and development of green and energy-saving products. Among them, wood-plastic composites have been widely studied and applied due to their excellent performance. However, a significant problem exists with wood-plastic composite boards used outdoors: poor thermal comfort in summer. This is because strong solar radiation can cause the surface temperature of the wood-plastic board to rise sharply, reaching up to 60°C, reducing thermal comfort when touched. Furthermore, commercially available wood-plastic composite boards typically consist of two layers: a protective top layer and a wood-plastic bottom layer. The bottom layer does not provide waterproofing, which can affect the lifespan of the wood-plastic composite board to some extent.

[0003] Therefore, it is necessary to adopt reasonable green cooling technologies and develop thermal management wood-plastic composite boards with self-generating surface cooling function, while achieving waterproof and moisture-proof effects so that their performance is not affected by rainwater or soil moisture, thereby extending the service life of the boards. Summary of the Invention

[0004] To address the aforementioned issues, a triple thermal management heat dissipation and moisture-proof wood-plastic composite board and its preparation method are provided. This triple thermal management heat dissipation and moisture-proof wood-plastic composite board consists of a radiation / reflection surface layer, a thermally conductive wood-plastic core layer, and a thermally conductive and waterproof bottom layer. It employs a three-layer melt co-extrusion process, where the surface layer, core layer, and bottom layer are first formed into separate molten flows, which then converge at the die head for three-layer co-extrusion. Finally, after cooling and shaping, the triple thermal management heat dissipation and moisture-proof wood-plastic composite board is obtained. By combining three thermal management strategies—strong solar reflection, high thermal radiation, and excellent thermal conductivity—the wood-plastic composite board achieves summer cooling, thereby improving thermal comfort upon direct contact with the human body. The bottom layer further provides waterproofing and moisture-proofing. This wood-plastic composite board can achieve heat dissipation and cooling in summer while simultaneously providing moisture protection. It features a reasonable structural design and a simple manufacturing process, making it suitable for various outdoor decorative wood-plastic panels, railings, garden benches, and exterior building applications.

[0005] According to one aspect of this application, a triple thermal management heat dissipation and moisture-proof wood-plastic composite board is provided, the wood-plastic composite board comprising a surface layer, a core layer and a bottom layer connected in sequence;

[0006] The surface layer comprises, by weight, 70-80 parts plastic, 10-30 parts abrasion resistant agent, 5-20 parts radiation / reflection filler, 2-4 parts compatibilizer, 1-3 parts antioxidant, and 2-4 parts UV stabilizer.

[0007] The core layer comprises, by weight, 50-60 parts wood flour, 20-40 parts plastic, 10-30 parts thermally conductive filler, 4-6 parts compatibilizer, 4-6 parts calcium carbonate, 1-3 parts polyethylene wax, and 1-2 parts antioxidant.

[0008] The bottom layer comprises, by weight, 70-90 parts plastic, 10-30 parts thermally conductive filler, and 1-3 parts antioxidant.

[0009] Optionally, the radiation / reflection filler is titanium dioxide.

[0010] Optionally, the titanium dioxide particle size is 0.3–1 μm. According to the Mie scattering principle, scattering occurs when the particle diameter is comparable to the wavelength of the radiation. This particle size range matches the visible light band of the solar spectrum (0.4–0.7 μm). If the particle size is too small, the scattering effect is not significant, and the solar reflectivity of the surface film is low; if the particle size is too large, Mie scattering fails, and the reflectivity improvement effect is not significant.

[0011] Optionally, the thermally conductive filler is hexagonal boron nitride.

[0012] Optionally, the particle size of the hexagonal boron nitride is 10–50 μm. If the particle size is too small, it will be difficult for the thermally conductive fillers to make contact and form a thermally conductive path; if the particle size is too large, it will increase the voids between the filler and the matrix, making it difficult to build a thermally conductive path, which will also lead to a poor thermal conductivity.

[0013] Optionally, the plastic is one or more of polyethylene, polypropylene, and polyvinyl chloride. It should be noted that the above list of plastics is not intended to limit the scope of this application, and those skilled in the art can choose suitable plastics for substitution.

[0014] Optionally, the wear-resistant agent is saline resin or ultra-high molecular weight polyethylene. Those skilled in the art will clearly understand that ultra-high molecular weight polyethylene (UHMWPE) is a linear polymer with a molecular weight greater than 1.5 million, possessing superior wear resistance.

[0015] Optionally, the wear-resistant agent is saline resin. It should be noted that the above list of wear-resistant agents is not intended to limit the scope of this application, and those skilled in the art can choose a suitable wear-resistant agent to substitute.

[0016] The compatibilizer is one or more selected from maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyvinyl chloride, silane coupling agents, and titanate coupling agents. It should be noted that the above list of compatibilizers does not constitute a limitation on the present application, and those skilled in the art can choose suitable compatibilizers for substitution.

[0017] Optionally, the antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 245; and / or,

[0018] The UV stabilizer is one or more of UV-531, UV-327, and UV-326. It should be noted that the above list of antioxidants and UV stabilizers does not constitute a limitation on the present application, and those skilled in the art can choose suitable antioxidants or UV stabilizers for substitution.

[0019] Optionally, the wood flour is one or more of pine wood flour, poplar wood flour, cypress wood flour, maple wood flour, and rice straw flour. It should be noted that the concept of wood flour in this application is quite broad, including not only conventional wood flour such as pine, poplar, cypress, and maple, but also rice straw flour. Of course, those skilled in the art can also choose other wood flour substitutes commonly used in the field of wood-plastic composite boards that can achieve the same function and effect.

[0020] Optionally, the wood flour in the core layer is waste wood flour, and the plastic in the core layer is recycled plastic. Since the core layer is located in the middle, using waste wood flour or recycled plastic does not affect performance while making full use of recycled resources and reducing costs.

[0021] Optionally, the wood-plastic composite board is prepared using a three-layer melt co-extrusion process. The surface layer, core layer, and bottom layer are first formed into different molten material flows, which are then converged at the composite die head for three-layer co-extrusion. Finally, the boards are cooled and shaped to obtain the final product. The three-layer melt co-extrusion process is a one-step molding process, with easily controllable processing parameters and high production efficiency.

[0022] Optionally, the surface layer thickness is 100–300 μm, the core layer thickness is 4–20 mm, and the bottom layer thickness is 50–200 μm. The surface layer film thickness is selected as 100–300 μm, within which the film can fully utilize its solar reflection effect. The core layer wood-plastic composite board thickness ranges from 4–20 mm, which can be determined according to actual application requirements. The bottom waterproof and thermally conductive film thickness ranges from 50–200 μm. Within this thickness range, the heat conduction path length is suitable, the contact between the boron nitride sheets is good, and the thermal conductivity is excellent. It should be noted that the above-mentioned ranges of the surface layer, core layer, and bottom layer thicknesses do not constitute a limitation on the solution of this application. For those skilled in the art, the thickness and ratio between each layer can be appropriately adjusted as needed. Based on the inventive concept of this application, adjusting the appropriate thickness ratio and finding a suitable combination scheme with better effects under different thickness requirements does not require excessive creative effort and is a basic skill of those skilled in the art.

[0023] According to another aspect of this application, a method for preparing any of the above-mentioned triple thermal management heat dissipation and moisture-proof wood-plastic composite boards is provided, the method comprising the following steps:

[0024] S1. Weigh each raw material according to the weight proportions;

[0025] S2. Mix the weighed plastic, abrasion resistant agent, radiation / reflective filler, compatibilizer, antioxidant, UV stabilizer and other surface materials into the first screw extruder, set the screw speed to 40-80 r / min and the extrusion temperature to 180-200℃;

[0026] S3. Mix the weighed wood flour, plastic, thermally conductive filler, compatibilizer, calcium carbonate, polyethylene wax, antioxidant and other core materials into the second screw extruder, set the screw speed to 40-60 r / min and the melt temperature to 150-180℃.

[0027] S4. Mix the weighed plastic, thermally conductive filler, antioxidant and other bottom materials into the third screw extruder, set the screw speed to 40-80 r / min and the melt temperature to 180-200℃;

[0028] S5. The three layers of molten material converge at the composite die head, and after three-layer co-extrusion and cooling and shaping, a triple thermal management heat dissipation and moisture-proof wood-plastic composite board is obtained.

[0029] According to another aspect of this application, the application of any of the above-mentioned triple thermal management heat dissipation and moisture-proof wood-plastic composite boards in outdoor wood products is provided.

[0030] Preferably, the wood products include various decorative wood-plastic composite panels, railings, garden benches, and exterior wall structures.

[0031] The beneficial effects of this application include, but are not limited to:

[0032] 1. The triple thermal management heat dissipation and moisture-proof wood-plastic composite board of this application is composed of a radiation / reflection surface layer, a thermally conductive wood-plastic core layer and a thermally conductive and waterproof bottom layer. By combining three thermal management strategies of strong solar reflection, high thermal radiation and excellent thermal conduction, the wood-plastic composite board can achieve summer cooling, thereby improving the thermal comfort of direct human contact. The bottom layer can further play a role in waterproofing and moisture-proofing.

[0033] 2. According to the triple thermal management heat dissipation and moisture-proof wood-plastic composite board of this application, the surface layer introduces radiation / reflection nanofillers. Due to the high refractive index of the radiation / reflection nanofillers themselves, the reflectivity of the surface layer to sunlight can be enhanced to reduce the absorption of solar heat. At the same time, the molecular vibration of the radiation / reflection nanofillers will increase the emissivity of the surface layer in the mid-infrared band to enhance the outward radiation of heat, which is beneficial to reducing the surface temperature of the wood-plastic composite board.

[0034] 3. According to the triple thermal management heat dissipation and moisture-proof wood-plastic composite board of this application, thermally conductive fillers are introduced into the core wood-plastic board. The thermally conductive fillers can contact each other in the substrate to form a thermally conductive network, thereby improving the thermal conductivity of the wood-plastic composite material, which can conduct the accumulated heat to the ground to further achieve the cooling effect.

[0035] 4. The triple thermal management heat dissipation and moisture-proof wood-plastic composite board according to this application has a bottom layer of thermally conductive and waterproof membrane, which can not only enhance the downward conduction of heat, but also play a waterproof and moisture-proof role, thus improving the service life of the wood-plastic composite board.

[0036] 5. The triple thermal management heat dissipation and moisture-proof wood-plastic composite board according to this application has a reasonable structural design and a simple manufacturing process, and is suitable for various outdoor decorative wood-plastic boards, railings, garden benches, exterior wall construction and other application scenarios. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0038] Figure 1 This is a schematic diagram of the heat dissipation principle of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board involved in this application.

[0039] Figure 2 The solar reflectance curves are for Comparative Example 1 and Examples 1-3 of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board surface layer involved in this application.

[0040] Figure 3 The mid-infrared emissivity curves are for Comparative Example 1 and Examples 1-3 of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board surface layer involved in this application.

[0041] Figure 4 The image shows a physical sample of Example 9 of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board involved in this application (the left image is a schematic diagram of the surface of the wood-plastic composite board; the right image is a schematic diagram of the cross-section of the three-layer wood-plastic composite board).

[0042] Figure 5 This is a scanning electron microscope (SEM) image of the core thermally conductive wood-plastic composite board in Example 9 of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board involved in this application. Detailed Implementation

[0043] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments. Unless otherwise specified, the raw materials and catalysts in the embodiments of the present application are all purchased through commercial channels.

[0044] It should be noted that in the specific embodiments described below, the radiation / reflection filler is titanium dioxide with a particle size of 0.2–1 μm; the thermally conductive filler is hexagonal boron nitride with a particle size of 10–50 μm; the wear-resistant agent is one or more of sarin resin and ultra-high molecular weight polyethylene; the compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyvinyl chloride, silane coupling agent, and titanate coupling agent; the plastic is one or more of polyethylene, polypropylene, and polyvinyl chloride; the UV stabilizer is one or more of UV-531, UV-327, and UV-326; and the waste wood powder is one or more of pine wood powder, poplar wood powder, cypress wood powder, maple wood powder, and rice straw powder. Furthermore, in the following embodiments, for ease of performance comparison, the surface layer thickness is controlled at 200 μm, the core layer thickness at 12 mm, and the bottom layer thickness at 120 μm. It should be noted that those skilled in the art can adjust the thickness of each layer as needed, or explore better implementation methods under different thickness ratios through a limited number of experiments. This does not require creative effort, and adjusting the thickness range of each layer in the present application can achieve the same improvement in thermal conductivity and waterproofing.

[0045] The present application solution will be described below through specific embodiments.

[0046] Example 1

[0047] In Example 1, the compatibilizer was maleic anhydride-grafted polyethylene, the antioxidant was antioxidant 1010, and the UV stabilizer was UV-531.

[0048] This embodiment relates to a method for preparing a triple thermal management heat dissipation and moisture-proof wood-plastic composite board, including the following steps:

[0049] (1) Weigh 70 parts of polyethylene, 10 parts of sarin resin, 5 parts of radiation / reflection filler, 2 parts of compatibilizer, 1 part of antioxidant, 2 parts of UV stabilizer and other surface materials and mix them into the first screw extruder. Set the screw speed to 40 r / min and the extrusion temperature to 180℃.

[0050] (2) Weigh 50 parts of waste poplar wood powder, 20 parts of recycled polyethylene, 4 parts of compatibilizer, 4 parts of calcium carbonate, 1 part of polyethylene wax, 1 part of antioxidant and other core materials and mix them into the second screw extruder. Set the screw speed to 40 r / min and the melting temperature to 150℃.

[0051] (3) Weigh 70 parts of polyethylene, 1 part of antioxidant and other bottom materials and mix them into the third screw extruder. Set the screw speed to 40 r / min and the melt temperature to 180℃.

[0052] (4) The three layers of molten material converge at the composite die head, and after three-layer co-extrusion and cooling and shaping, the triple thermal management heat dissipation and moisture-proof wood-plastic composite board 1# is obtained.

[0053] Example 2

[0054] The difference between this embodiment and Example 1 is that: the radiation / reflection filler is 10 parts, the compatibilizer is maleic anhydride-grafted polypropylene, the antioxidant is antioxidant 168, the UV stabilizer is UV-327, and the remaining substances and preparation steps are the same as in Example 1, thus obtaining wood-plastic composite board 2#.

[0055] Example 3

[0056] The difference between this embodiment and Example 1 is that: the radiation / reflection filler is 20 parts, the compatibilizer is maleic anhydride-grafted polyvinyl chloride, the antioxidant is antioxidant 245, the UV stabilizer is UV-326, and the remaining substances and preparation steps are the same as in Example 1, thus obtaining wood-plastic composite board 3#.

[0057] Example 4

[0058] In Example 4, the compatibilizer was a silane coupling agent, the antioxidant was antioxidant 1010, and the UV stabilizer was UV-327.

[0059] This embodiment relates to a method for preparing a triple thermal management heat dissipation and moisture-proof wood-plastic composite board, including the following steps:

[0060] (1) Weigh 80 parts of polyethylene, 30 parts of sarin resin, 20 parts of radiation / reflection filler, 4 parts of compatibilizer, 3 parts of antioxidant, 4 parts of UV stabilizer and other surface materials and mix them into the first screw extruder. Set the screw speed to 60 r / min and the extrusion temperature to 200℃.

[0061] (2) Weigh 60 parts of waste pine wood powder, 40 parts of recycled polypropylene, 10 parts of thermally conductive filler, 6 parts of compatibilizer, 6 parts of calcium carbonate, 3 parts of polyethylene wax, 2 parts of antioxidant and other core materials and mix them into the second screw extruder. Set the screw speed to 60 r / min and the melt temperature to 180℃.

[0062] (3) Weigh 90 parts of polyethylene, 3 parts of antioxidant and other bottom materials and mix them into the third screw extruder. Set the screw speed to 80 r / min and the melt temperature to 200℃.

[0063] (4) The three layers of molten material converge at the composite die head, and after three-layer co-extrusion and cooling and shaping, the triple thermal management heat dissipation and moisture-proof wood-plastic composite board 4# is obtained.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 4 is that the core layer thermally conductive filler is 20 parts, while the remaining materials and preparation steps are the same as in embodiment 4, thus obtaining wood-plastic composite board 5#.

[0066] Example 6

[0067] The difference between this embodiment and embodiment 4 is that the core layer thermally conductive filler is 30 parts, while the remaining materials and preparation steps are the same as in embodiment 4, thus obtaining wood-plastic composite board 6#.

[0068] Example 7

[0069] In Example 7, the compatibilizer is a titanate coupling agent, the antioxidant is antioxidant 1010, and the UV stabilizer is UV-326.

[0070] This embodiment relates to a method for preparing a triple thermal management heat dissipation and moisture-proof wood-plastic composite board, including the following steps:

[0071] (1) Weigh 75 parts of polyethylene, 20 parts of sarin resin, 20 parts of radiation / reflection filler, 3 parts of compatibilizer, 2 parts of antioxidant, 3 parts of UV stabilizer and other surface materials and mix them into the first screw extruder. Set the screw speed to 50 r / min and the extrusion temperature to 160℃.

[0072] (2) Weigh 55 parts of waste cypress wood powder, 30 parts of recycled polyvinyl chloride, 30 parts of thermally conductive filler, 5 parts of compatibilizer, 5 parts of calcium carbonate, 2 parts of polyethylene wax, 1 part of antioxidant and other core materials and mix them into the second screw extruder. Set the screw speed to 50 r / min and the melt temperature to 170℃.

[0073] (3) Weigh 70 parts of polyvinyl chloride, 10 parts of thermally conductive filler, 1 part of antioxidant and other bottom materials and mix them into the third screw extruder. Set the screw speed to 40 r / min and the melt temperature to 180℃.

[0074] (4) The three layers of molten material converge at the composite die head, and after three-layer co-extrusion and cooling and shaping, the triple thermal management heat dissipation and moisture-proof wood-plastic composite board 7# is obtained.

[0075] Example 8

[0076] The difference between this embodiment and embodiment 7 is that the bottom thermally conductive filler is 20 parts, while the remaining materials and preparation steps are the same as in embodiment 7, thus obtaining wood-plastic composite board 8#.

[0077] Example 9

[0078] The difference between this embodiment and embodiment 7 is that the bottom thermally conductive filler is 30 parts, while the remaining materials and preparation steps are the same as in embodiment 7, thus obtaining wood-plastic composite board 9#.

[0079] Example 10

[0080] The difference between this embodiment and embodiment 9 is that the sarin resin is replaced with an equal amount of ultra-high molecular weight polyethylene, while the other substances and preparation steps are the same as in embodiment 9, thus obtaining wood-plastic composite board 10#.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that the surface layer does not contain radiation / reflection fillers, while the remaining materials and preparation steps are the same as in Example 1, thus obtaining wood-plastic composite board D1#.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 4 is that the core layer does not contain thermally conductive filler, while the remaining materials and preparation steps are the same as in Example 4, thus obtaining wood-plastic composite board D2#.

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 7 is that the bottom layer does not contain thermally conductive filler, while the remaining materials and preparation steps are the same as in Example 7, thus obtaining wood-plastic composite board D3#.

[0087] Comparative Example 4

[0088] The difference between this comparative example and Example 9 is that it has a two-layer structure, with only a surface layer and a core layer of wood-plastic composite board, no bottom layer, and no radiation / reflection filler in the surface layer and no thermally conductive filler in the core layer. The remaining materials and preparation steps are the same as in Example 9, thus obtaining wood-plastic composite board D4#.

[0089] Comparative Example 5

[0090] The difference between this comparative example and Example 9 is that it has a two-layer structure, with only a surface layer and a core layer of wood-plastic composite board, no bottom layer, and no thermally conductive filler in the core layer. The other materials and preparation steps are the same as in Example 9, thus obtaining wood-plastic composite board D5#.

[0091] Comparative Example 6

[0092] The difference between this comparative example and Example 9 is that it has a two-layer structure, with only a surface layer and a core layer of wood-plastic composite board, and no bottom layer. The other materials and preparation steps are the same as in Example 9, thus obtaining wood-plastic composite board D6#.

[0093] Test Example 1: Surface Solar Reflectivity and Mid-Infrared Emissivity Test

[0094] The solar reflectance and mid-infrared emissivity of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board surface layers obtained in Examples 1-3 and Comparative Example 1 were tested respectively. For solar reflectance, a UV spectrophotometer with an integrating sphere was used in reflectance mode to obtain reflectance curves from 300 to 2300 nm. Then, a Fourier transform infrared spectrometer with a gold integrating sphere attachment was used to measure the mid-infrared band (8-13 μm) reflectance and transmittance of the film. The mid-infrared absorptivity was calculated using the formula: reflectance + transmittance + absorptivity = 100%. Furthermore, according to Kirchhoff's law, absorptivity and emissivity are equal, so the calculated mid-infrared absorptivity is the same as the mid-infrared emissivity. The solar reflectance and mid-infrared emissivity test curves are shown below. Figure 2 and Figure 3 As shown in Table 1, the calculated average solar reflectance and average mid-infrared emissivity results are presented.

[0095] Table 1. Test results of solar reflectivity and mid-infrared emissivity

[0096] Test number Average solar reflectance (%) Average mid-infrared emissivity (%) Example 1 70 63 Example 2 76 74 Example 3 84 90 Comparative Example 1 12 56

[0097] As shown in Table 1, compared with Comparative Example 1 (without radiation / reflection filler), the solar reflectance and mid-infrared emissivity of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board surface layer with added radiation / reflection filler are significantly improved. Specifically, after adding 20 parts of radiation / reflection filler, the solar reflectance increased from 12% to 84%, and the mid-infrared emissivity increased from 56% to 90%, exhibiting optimal spectral performance. This not only reduces the absorption of sunlight by the surface layer but also emits heat, increasing the heat dissipation of the wood-plastic composite board.

[0098] Test Example 2: Thermal Conductivity Test of Core Layer Wood-Plastic Composite Board

[0099] The thermal conductivity of the core layer of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board obtained in Examples 4-6 and Comparative Example 2 was tested using a laser thermal conductivity meter. The samples were first cut into circles with a diameter of 25.4 mm, sprayed with graphite and placed in a sample tray. The experimental program was then set to conduct the test. Each sample was tested 5 times. The test results are shown in Table 2.

[0100] Table 2 Thermal conductivity test results

[0101] Test number Thermal conductivity (W / (m·K)) Example 4 0.72 Example 5 1.25 Example 6 1.86 Comparative Example 2 0.41

[0102] As shown in Table 2, compared with Comparative Example 2 (without thermally conductive filler), the thermal conductivity of the core layer wood-plastic composite board with added thermally conductive filler was significantly improved. Among them, the core layer wood-plastic composite board with 30 parts of thermally conductive filler exhibited the best thermal conductivity, increasing from 0.41 W / (m·K) to 1.86 W / (m·K). This is because the connections between the lamellar boron nitride particles gradually improved the thermal conductive network, thereby enhancing the thermal conductivity of the core layer wood-plastic composite board and facilitating the downward conduction of heat from the surface layer.

[0103] Test Example 3: Thermal Conductivity Test of the Underlying Thermally Conductive and Waterproof Membrane

[0104] The thermal conductivity of the bottom layer of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board obtained in Examples 7-10 and Comparative Example 3 was tested using a laser thermal conductivity meter. The test steps were the same as those in Test Example 2. The test results are shown in Table 3.

[0105] Table 3 Thermal conductivity test results

[0106]

[0107]

[0108] As shown in Table 3, compared with Comparative Example 3 (without thermally conductive filler), the thermal conductivity of the bottom layer of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board with added thermally conductive filler is significantly improved. The bottom layer with 30 parts of thermally conductive filler exhibits the best thermal conductivity, increasing from 0.47 W / (m·K) to 1.37 W / (m·K). This is because the connections between the lamellar boron nitride particles gradually improve the thermal conductivity network, giving the bottom layer excellent thermal conductivity and facilitating the downward conduction of heat accumulated in the core layer.

[0109] Test Example 4: Outdoor Temperature Drop Comparison Test

[0110] To realistically test the cooling performance of triple thermal management heat dissipation and moisture-proof wood-plastic composite boards under strong summer sunlight, Examples 9, 10, and Comparative Examples 4-6 were placed outdoors in direct sunlight on a sunny day. The surface temperature and cooling results are shown in Table 4, where the cooling effect refers to the temperature drop of the wood-plastic composite board compared to Comparative Example 4.

[0111] Table 4. Results of Cooling Effect Test

[0112] Test number Surface temperature (°C) Cooling effect (°C) Example 9 51.2 15.0 Example 10 51.0 15.2 Comparative Example 4 66.2 0 Comparative Example 5 58.7 7.5 Comparative Example 6 52.2 14.0

[0113] As shown in Table 4, the surface temperatures of the triple thermal management heat dissipation and moisture-proof wood-plastic composite boards in Examples 9, 10, 5, and 6 are all lower than those of the ordinary double-layer wood-plastic board in Comparative Example 4. Examples 9 and 10 show a temperature drop of nearly 15°C, demonstrating a significant cooling advantage. Therefore, the cooling advantage achieved by combining the three thermal management strategies of enhanced solar reflection, mid-infrared emission, and enhanced thermal conductivity employed in this application can significantly improve the surface thermal comfort of wood-plastic boards in summer.

[0114] Test Example 5: Water Absorption Rate Test

[0115] Water absorption tests were conducted on Examples 9, 10, and Comparative Examples 4-6, referring to the test method in national standard GB / T29418-2012. The masses before and after drying and soaking in water for 24 hours were weighed, and then the results were calculated using the formula (m... b -m a ) / m a The water absorption rate is calculated by multiplying by 100%, where m b and m b The values ​​represent the mass of the wood-plastic composite board before and after immersion in water, respectively. The water absorption rate results are shown in Table 5.

[0116] Table 5. Results of water absorption rate test

[0117] Test number Water absorption rate (%) Example 9 0.2 Example 10 0.2 Comparative Example 4 1.6 Comparative Example 5 1.2 Comparative Example 6 0.9

[0118] According to the data in Table 5, compared with the ordinary double-layer wood-plastic composite (Comparative Example 4), the water absorption rate of the triple thermal management heat dissipation and moisture-proof wood-plastic composite boards of Examples 9, 10, 5, and 6 all decreased. Examples 9 and 10 showed the best results, decreasing from 1.6% to 0.2%. The reason why the water absorption rates of Comparative Examples 5 and 6 are lower than those of Comparative Example 4, even though they are also double-layer wood-plastic composite boards, is due to the hydrophobic effect of the titanium dioxide nanoparticles in the surface layer and the boron nitride filler in the core layer. In addition, the addition of these materials also reduces the volume percentage of wood powder, thereby lowering the water absorption rate of the wood-plastic composite board. Example 9 of this application showed the lowest water absorption rate of only 0.2%, demonstrating that the three-layer structure used in this application, specifically the top and bottom layers encapsulating the core wood-plastic composite, can significantly reduce the water absorption rate of the wood-plastic composite board and effectively extend its service life.

[0119] Figure 4 The image shows a sample of Example 9. The left image shows the surface of the wood-plastic composite board, which is smooth and free of defects. The right image shows a cross-sectional view of the three-layer wood-plastic composite board, which clearly shows that the core thermally conductive wood-plastic board is covered by the surface radiation / reflection film and the bottom waterproof thermally conductive film, which can fully play the role of waterproofing and moisture-proofing. Moreover, due to the melt co-extrusion process, the three layers are very tight between the interfaces and there is no delamination, which can realize the application in multiple scenarios.

[0120] Figure 5 The image shown is a scanning electron microscope image of the core layer thermally conductive wood-plastic composite board in Example 9. It can be seen that the boron nitride sheet-like structures are in contact with each other, forming a good thermally conductive network in the matrix resin, which can significantly improve the thermal conductivity of the core layer wood-plastic composite board.

[0121] Experimental Example 1: Screening of Radiation / Reflection Fillers

[0122] Since the reflectivity of the fillers is not significantly different, the selection of surface radiation / reflection fillers is mainly based on refractive index. A higher refractive index results in a greater difference in refractive index between the filler and high-density polyethylene (refractive index 1.54), leading to better solar reflection, which is highly beneficial for cooling under strong sunlight. Barium sulfate (1.6), calcium carbonate (1.7), zirconium dioxide (2.2), and titanium dioxide (2.5) were initially selected as radiation / reflection fillers. These fillers were then used in equal mass fractions (20 parts) in the surface layer for reflectivity testing. The average reflectivity is shown in Table 6.

[0123] Table 6. Results of Average Solar Reflectivity Test

[0124] Radiation / Reflection Filler Average solar reflectance (%) Barium sulfate 20.9 Calcium carbonate 30.6 Zirconium dioxide 64.9 Titanium dioxide 84 No filler 12

[0125] It can be seen that titanium dioxide has the best reflection enhancement effect at the same mass fraction, so it was selected as the radiation / reflection filler. Furthermore, subsequent experiments show that titanium dioxide, when combined with other components in this application, can achieve excellent cooling effect.

[0126] Experiment Example 2: Screening of Thermally Conductive Fillers

[0127] To improve the thermal conductivity of the core wood-plastic composite board and the bottom waterproof thermally conductive film, several thermally conductive fillers, including silicon carbide, spherical alumina, spherical aluminum nitride, spherical boron nitride, and flake boron nitride, were initially screened. Then, taking the core wood-plastic composite board as an example, the thermal conductivity of the wood-plastic composite board filled with different thermally conductive fillers (content of 20 parts) was tested, as shown in Table 7.

[0128] Table 7 Thermal conductivity test results

[0129] Thermally conductive filler Thermal conductivity (W / (m·K)) silicon carbide 1.40 Spherical alumina 0.68 Spherical aluminum nitride 0.80 Spherical boron nitride 1.03 Plate-shaped boron nitride 1.25 No thermally conductive filler 0.41

[0130] The test results show that, for the same mass fraction of thermally conductive fillers, the thermal conductivity enhancement effect is in the following order: silicon carbide > lamellar boron nitride > spherical boron nitride > spherical aluminum nitride > spherical alumina. This is due to two main reasons: firstly, the thermal conductivity of the fillers themselves varies; secondly, the fillers' ability to contact each other within the matrix resin and their ease of constructing a complete thermal conductivity pathway. Lamellar boron nitride not only possesses good thermal conductivity but also an excellent aspect ratio (e.g., ...). Figure 5As shown in the image, it also possesses a certain degree of hydrophobicity, which is highly beneficial for constructing heat conduction paths and achieving moisture-proof properties in wood-plastic composite boards. Considering both overall cost and improved thermal conductivity, appropriately sized flake boron nitride is chosen as the thermally conductive reinforcing filler for both the core wood-plastic composite board and the bottom waterproof thermally conductive film.

[0131] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a triple heat management heat dissipation moisture-proof wood-plastic composite board, characterized in that, The wood-plastic composite board includes a surface layer, a core layer, and a bottom layer connected in sequence, wherein the surface layer has a thickness of 100~300μm, the core layer has a thickness of 4~20mm, and the bottom layer has a thickness of 50~200μm; The surface layer comprises, by weight, 70-80 parts plastic, 10-30 parts wear-resistant agent, 5-20 parts radiation / reflective filler, 2-4 parts compatibilizer, 1-3 parts antioxidant, and 2-4 parts UV stabilizer; the core layer comprises, by weight, 50-60 parts wood flour, 20-40 parts plastic, 10-30 parts thermally conductive filler, 4-6 parts compatibilizer, 4-6 parts calcium carbonate, 1-3 parts polyethylene wax, and 1-2 parts antioxidant; the bottom layer comprises, by weight, 70-90 parts plastic, 10-30 parts thermally conductive filler, and 1-3 parts antioxidant. The radiation / reflection filler is titanium dioxide with a particle size of 0.3~1μm; the thermally conductive filler is hexagonal boron nitride with a particle size of 10~50μm; the plastic is one or more of polyethylene, polypropylene, and polyvinyl chloride; the wear-resistant agent is saline resin or ultra-high molecular weight polyethylene; the compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyvinyl chloride, silane coupling agent, and titanate coupling agent. The wood-plastic composite board is prepared using a three-layer melt co-extrusion process. The surface layer, core layer, and bottom layer are first formed into different molten material flows, which are then converged at the composite die head for three-layer co-extrusion. Finally, the boards are cooled and shaped to obtain the final product. The specific preparation method includes the following steps: S1. Weigh each raw material according to the weight proportions; S2. Mix the weighed plastic, abrasion resistant agent, radiation / reflective filler, compatibilizer, antioxidant, and UV stabilizer into the first screw extruder, set the screw speed to 40~80 r / min, and the extrusion temperature to 180~200℃. S3. Mix the weighed wood flour, plastic, thermally conductive filler, compatibilizer, calcium carbonate, polyethylene wax, antioxidant core material into the second screw extruder, set the screw speed to 40~60 r / min, and the melt temperature to 150~180℃. S4. Mix the weighed plastic, thermally conductive filler, and antioxidant bottom material into the third screw extruder, set the screw speed to 40~80 r / min, and the melt temperature to 180~200℃; S5. The three layers of molten material converge at the composite die head, and after three-layer co-extrusion and cooling and shaping, a triple thermal management heat dissipation and moisture-proof wood-plastic composite board is obtained.

2. The preparation method of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board according to claim 1, characterized in that, The antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 245; and / or, The UV stabilizer is one or more of UV-531, UV-327, and UV-326.

3. The method for preparing the triple thermal management heat dissipation and moisture-proof wood-plastic composite board according to claim 1, characterized in that, The wood powder is one or more of the following: pine powder, poplar powder, cypress powder, maple powder, and rice straw powder.

4. The preparation method of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board according to claim 1, characterized in that, The wood flour in the core layer is waste wood flour, and the plastic in the core layer is recycled plastic.

5. The application of the triple thermal management heat dissipation and moisture-proof wood-plastic composite board obtained by the preparation method according to any one of claims 1 to 4 in outdoor wood products.

6. The application according to claim 5, characterized in that, The wood products include decorative wood-plastic composite panels, railings, garden benches, and exterior wall construction.

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